How to create a link between two objects using the link function

Low-code
, ,
#1

Previously, we have seen how to create a link between two objects using hypi.ids.

link function also creates a link between two objects. The link can be a one-to-one reference or a one-to-many reference.

Let’s see how to use the link function. We will use the below schema.

type OldObject {
    field1: String 
}

type NewObject {
    fld1: String
    fld2: OldObject
    fld3: [OldObject]
}
  • There is a one-to-one reference between NewObject and OldObject via field fld2.
  • There are one-to-many references between NewObject and OldObject via field fld3 array of type OldObject.
  • Link function has the below signature.
link(
    from:HypiMutationType!
    to:HypiMutationType!
    via:String!
    whereFromID:String!
    andToID:String!
):Boolean!
  • from and to fields indicate the data types to create a link
  • via is the field of data type ‘to’ in the data type ‘from’
  • whereFromID and andToID are the hypi.id of the objects to be linked.

Let’s create objects of type OldObject and NewObject

#OldObject 
mutation {
  upsert(
    values: {
      OldObject: [
        { field1: "Hypi's Low code Platform!" }
        { field1: "Hypi easy to use backend-as-a-service" }
      ]
    }
  ) {
    id
  }
}
# Result
{
  "data": {
    "upsert": [
      {
        "id": "01FHZM11Q6MG3NKVR8D14QGKFH"
      },
      {
        "id": "01FHZM11Q9C03SJK1XM9SK603R"
      }
    ]
  }
}

#NewObject
mutation {
  upsert(values: { NewObject: [{ fld1: "Create link between two objects" }] }) {
    id
  }
}
#result
{
  "data": {
    "upsert": [
      {
        "id": "01FHZM6G4P3N7AARH85755VX0X"
      }
    ]
  }
}

Sample Query

Now we will link the created objects using the link function

#one-to-one reference
mutation {
  link(
    from: NewObject
    to: OldObject
    via: "fld2"
    whereFromID: "01FHZM6G4P3N7AARH85755VX0X"
    andToID: "01FHZM11Q6MG3NKVR8D14QGKFH"
  )
}
#one-to-many references
mutation {
  link(
    from: NewObject
    to: OldObject
    via: "fld3"
    whereFromID: "01FHZM6G4P3N7AARH85755VX0X"
    andToID: "01FHZM11Q6MG3NKVR8D14QGKFH"
  )
}
mutation {
  link(
    from: NewObject
    to: OldObject
    via: "fld3"
    whereFromID: "01FHZM6G4P3N7AARH85755VX0X"
    andToID: "01FHZM11Q9C03SJK1XM9SK603R"
  )
}
#results
{
  "data": {
    "link": true
  }
}

Output

The function returns true if the linking was successful otherwise false.
We will check the linked data using get function.

{
  get(type: NewObject, id: "01FHZM6G4P3N7AARH85755VX0X") {
    ... on NewObject {
      fld1
      fld2 {
        field1
      }
      fld3 {
        field1
      }
    }
  }
}
#result
{
  "data": {
    "get": {
      "fld1": "Create link between two objects",
      "fld2": {
        "field1": "Hypi's Low code Platform!"
      },
      "fld3": [
        {
          "field1": "Hypi's Low code Platform!"
        },
        {
          "field1": "Hypi easy to use backend-as-a-service"
        }
      ]
    }
  }
}

Query with Variables

mutation linkObjecs(
  $from: HypiMutationType!
  $to: HypiMutationType!
  $via: String!
  $whereFromID: String!
  $andToID: String!
) {
  link(
    from: $from
    to: $to
    via: $via
    whereFromID: $whereFromID
    andToID: $andToID
  )
}

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